Ultrasound diagnostic apparatus and program

Abstract

To suppress the occurrence of a speckle pattern in a case where a DMAS-system beamforming for multiplying and summing signals is used as a beamforming system.SOLUTION: An ultrasound diagnostic apparatus of an embodiment multiplies reception signals between different elements, out of a plurality of reception signals output from a plurality of elements, and executes an ultrasonic beamforming system for summing signals obtained as a result of the multiplication. The ultrasound diagnostic apparatus of the embodiment comprises a weight calculation unit and an application unit. The weight calculation unit calculates a weight coefficient based on the correlation between the multiplied reception signals. The application unit applies the weight coefficient to the signals obtained as a result of the multiplication.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The embodiments disclosed in the present specification and drawings relate to an ultrasound diagnostic apparatus and a program. [Background technology]

[0002] Delay and Sum (DAS) is a commonly used receive beamforming technique implemented by ultrasound diagnostic equipment. In recent years, various methods different from the DAS method have been proposed. For example, Minimum Variance Beamforming, Coherence Factor Imaging, and Delay Multiply and Sum Beamforming (DMAS) are well known. Among these, DMAS multiplies and adds signals output from different elements (piezoelectric transducers, piezoelectric elements).

[0003] As described above, in DMAS, signals output from different elements are multiplied. Therefore, compared to ultrasonic image data obtained using DAS, ultrasonic image data obtained using DMAS is sensitive to time lags (time differences, phase differences) between output signals, which manifests as, for example, larger amplitude fluctuations in speckle patterns (speckle noise). That is, compared to ultrasonic image data obtained using DAS, ultrasonic image data obtained using DMAS displays an emphasized speckle pattern. As described above, in DMAS, signals are multiplied, which increases the amplitude fluctuations in speckle echoes, resulting in reduced contrast resolution. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-8933 [Patent Document 2] Japanese Patent Application Publication No. 2018-187014 [Patent Document 3] Special Publication No. 2009-536855 [Patent Document 4] Japanese Patent Application Laid-Open No. 2015-213673 [Non-patent literature]

[0005] [Non-Patent Document 1] The Delay Multiply and Sum Beamforming Algorithm in Ultrasound B-Mode Medical Imaging, IEEE Transaction 2015. [Non-patent document 2] Enhanced Ultrasound Harmonic Imaging Using the Filtered-Delay Multiply and Sum Beamformer, IEEE Conference Paper 2017. Summary of the Invention [Problem to be solved by the invention]

[0006] One of the problems to be solved by the embodiments disclosed in this specification and the drawings is to suppress the occurrence of speckle patterns when a method of multiplying and adding signals is used as a beamforming method. However, the problems to be solved by the embodiments disclosed in this specification and the drawings are not limited to the above problem. Problems corresponding to the effects of each configuration shown in the embodiments described below can also be positioned as other problems. [Means for solving the problem]

[0007] An ultrasound diagnostic apparatus according to an embodiment performs ultrasound beamforming by multiplying received signals output from multiple elements by received signals from different elements and adding the signals obtained as a result of the multiplication. The ultrasound diagnostic apparatus according to an embodiment includes a weight calculation unit and an application unit. The weight calculation unit calculates a weighting factor based on the correlation between the multiplied received signals. The application unit applies the weighting factor to the signals obtained as a result of the multiplication. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram showing an example of the configuration of an ultrasonic diagnostic apparatus according to the first embodiment. [Figure 2] FIG. 2 is a diagram showing an example of the configuration of a beam former that performs beam forming of the DMAS system in the receiving circuit according to the first embodiment. [Figure 3] FIG. 3 is a flowchart showing an example of the flow of processing executed by the DMAS beamformer according to the first embodiment. [Figure 4] FIG. 4 is a diagram showing an example of an ultrasound image based on ultrasound image data obtained using a conventional DMAS. [Figure 5] FIG. 5 is a diagram showing an example of an ultrasound image based on ultrasound image data generated by the ultrasound diagnostic apparatus according to the first embodiment. [Figure 6] FIG. 6 is a diagram illustrating an example of the configuration of a beam former that performs beam forming of the DMAS system in a receiving circuit according to a modification of the first embodiment. [Figure 7] FIG. 7 is a diagram illustrating an example of a part of the configuration of a beamformer according to the second embodiment. [Figure 8] FIG. 8 is a diagram showing an example of an ultrasound image based on ultrasound image data generated by the ultrasound diagnostic apparatus according to the second embodiment. [Figure 9] FIG. 9 is a diagram illustrating an example of a part of the configuration of a beamformer according to the third embodiment. [Figure 10]FIG. 10 is a diagram illustrating an example of a part of the configuration of a beamformer according to the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, ultrasonic diagnostic apparatuses and programs according to embodiments and modifications will be described with reference to the drawings.

[0010] (First embodiment) Fig. 1 is a block diagram showing an example of the configuration of an ultrasound diagnostic apparatus 1 according to the first embodiment. As illustrated in Fig. 1, the ultrasound diagnostic apparatus 1 according to the first embodiment includes an apparatus main body 100, an ultrasound probe 101, an input device 102, and a display 103. In the first embodiment, the ultrasound diagnostic apparatus 1 executes a DMAS method, which is an ultrasound beamforming method that multiplies received signals between different elements among a plurality of received signals output from a plurality of elements of the ultrasound probe 101, and adds up the signals obtained as a result of the multiplication.

[0011] The ultrasonic probe 101 includes, for example, a plurality of elements (piezoelectric vibrators, piezoelectric elements). These elements generate ultrasonic waves based on a drive signal supplied from a transmission circuit 111 of a transmission / reception circuit 110 included in the device main body 100. Specifically, the elements generate ultrasonic waves having a waveform corresponding to the transmission drive voltage when a voltage (transmission drive voltage) is applied by the transmission circuit 111. The waveform of the transmission drive voltage indicated by the drive signal is the waveform of the voltage applied to the plurality of elements. That is, the ultrasonic probe 101 transmits ultrasonic waves corresponding to the magnitude of the applied transmission drive voltage. The ultrasonic probe 101 also receives reflected waves from the subject P, converts them into received signals (reflected wave signals), which are electrical signals, and outputs the received signals to the device main body 100. The ultrasonic probe 101 also includes, for example, a matching layer provided on the elements and a backing material that prevents ultrasonic waves from propagating backward from the elements. The ultrasonic probe 101 is detachably connected to the device main body 100.

[0012] When ultrasonic waves are transmitted from the ultrasonic probe 101 to the subject P, the transmitted ultrasonic waves are reflected successively by discontinuous surfaces of acoustic impedance in the tissues of the subject P and are received as reflected waves by multiple elements of the ultrasonic probe 101. The amplitude of the received reflected waves depends on the difference in acoustic impedance at the discontinuous surfaces from which the ultrasonic waves are reflected. When the transmitted ultrasonic pulse is reflected by the surface of a moving blood flow, heart wall, or the like, the reflected waves undergo a frequency shift due to the Doppler effect depending on the velocity component of the moving object in the direction of ultrasonic transmission. The ultrasonic probe 101 then outputs the received signals to the receiving circuit 112 of the transmitting / receiving circuit 110, which will be described later.

[0013] The ultrasonic probe 101 is detachably attached to the device main body 100. When scanning a two-dimensional region inside the subject P (two-dimensional scanning), the operator connects, for example, a 1D array probe in which multiple elements are arranged in a row to the device main body 100 as the ultrasonic probe 101. Types of 1D array probes include linear ultrasonic probes, convex ultrasonic probes, and sector ultrasonic probes. When scanning a three-dimensional region inside the subject P (three-dimensional scanning), the operator connects, for example, a mechanical 4D probe or a 2D array probe to the device main body 100 as the ultrasonic probe 101. A mechanical 4D probe is capable of two-dimensional scanning using multiple elements arranged in a row like a 1D array probe, and is also capable of three-dimensional scanning by swinging the multiple elements at a predetermined angle (swing angle). A 2D array probe is capable of three-dimensional scanning using multiple elements arranged in a matrix, and is also capable of two-dimensional scanning by focusing and transmitting ultrasonic waves.

[0014] The input device 102 is realized by input means such as a mouse, keyboard, button, panel switch, touch command screen, foot switch, trackball, joystick, etc. The input device 102 receives various setting requests from the operator of the ultrasound diagnostic apparatus 1 and transfers the received various setting requests to the apparatus main body 100.

[0015] The display 103 displays, for example, a GUI (Graphical User Interface) that allows the operator of the ultrasound diagnostic apparatus 1 to input various setting requests using the input device 102, and displays ultrasound images based on ultrasound image data generated in the apparatus main body 100. The display 103 is realized by a liquid crystal monitor, a CRT (Cathode Ray Tube) monitor, or the like.

[0016] The device main body 100 generates ultrasound image data based on reception signals transmitted from the ultrasound probe 101. Note that ultrasound image data is an example of image data. The device main body 100 can generate two-dimensional ultrasound image data based on reception signals transmitted from the ultrasound probe 101 corresponding to a two-dimensional region of the subject P. The device main body 100 can also generate three-dimensional ultrasound image data based on reception signals transmitted from the ultrasound probe 101 corresponding to a three-dimensional region of the subject P. As shown in FIG. 1, the device main body 100 includes a transmission / reception circuit 110, a buffer memory 120, a signal processing circuit 130, an image generation circuit 140, an image memory 150, a storage circuit 160, and a control circuit 170.

[0017] The transmission / reception circuit 110, under the control of the control circuit 170, causes the ultrasonic probe 101 to transmit ultrasonic waves and causes the ultrasonic probe 101 to receive reflected waves of the ultrasonic waves. In other words, the transmission / reception circuit 110 performs scanning via the ultrasonic probe 101. Note that scanning is also referred to as scanning, ultrasonic scanning, or ultrasonic scanning. The transmission / reception circuit 110 is an example of a transmission / reception unit. The transmission / reception circuit 110 has a transmission circuit 111 and a reception circuit 112. The transmission circuit 111 is an example of a transmission unit, and the reception circuit 112 is an example of a reception unit.

[0018] The transmission circuit 111, under the control of the control circuit 170, causes the ultrasonic probe 101 to transmit ultrasonic waves. The transmission circuit 111 has a rate pulser generating circuit, a transmission delay circuit, and a transmission pulser. The transmission circuit 111 supplies a drive signal to the ultrasonic probe 101. When scanning a two-dimensional region within the subject P, the transmission circuit 111 causes the ultrasonic probe 101 to transmit an ultrasonic beam for scanning the two-dimensional region. When scanning a three-dimensional region within the subject P, the transmission circuit 111 causes the ultrasonic probe 101 to transmit an ultrasonic beam for scanning the three-dimensional region.

[0019] The rate pulser generating circuit, under the control of the control circuit 170, repeatedly generates rate pulses for forming a transmission ultrasound wave (transmission beam) at a predetermined rate frequency (PRF: Pulse Repetition Frequency). The rate pulses pass through a transmission delay circuit, so that voltages with different transmission delay times are applied to the transmission pulser. For example, the transmission delay circuit imparts a transmission delay time for each element, which is required to focus the ultrasound waves generated from the ultrasound probe 101 into a beam and determine the transmission directivity, to each rate pulse generated by the rate pulser generating circuit. The transmission pulser supplies a drive signal (drive pulse) to the ultrasound probe 101 at a timing based on the rate pulse. That is, the transmission pulser applies a voltage (transmission drive voltage) having a waveform indicated by the drive signal to the ultrasound probe 101 at a timing based on the rate pulse. The transmission delay circuit arbitrarily adjusts the transmission direction of ultrasound waves from the element surface by changing the transmission delay time imparted to each rate pulse.

[0020] The driving pulse is transmitted from the transmitting pulser via a cable to the elements in the ultrasonic probe 101, and then converted from an electrical signal into mechanical vibration in the elements. That is, when a voltage is applied to the elements, the elements vibrate mechanically. Ultrasound waves generated by this mechanical vibration are transmitted into the living body (inside the subject P). Here, the ultrasonic waves, which have different transmission delay times for each element, are focused and propagate in a predetermined direction.

[0021] The transmission circuit 111 has a function of being able to instantaneously change the transmission frequency, transmission drive voltage, etc. in order to execute a predetermined scanning sequence under the control of the control circuit 170. In particular, the change in the transmission drive voltage is realized by a linear amplifier type oscillation circuit that can instantaneously switch the value of the transmission drive voltage, or a mechanism that electrically switches between multiple power supply units.

[0022] The reflected waves of the ultrasonic waves transmitted by the ultrasonic probe 101 reach the elements inside the ultrasonic probe 101, and are then converted from mechanical vibrations into electrical signals (received signals) in the elements, and the received signals are input to the receiving circuit 112. The receiving circuit 112 has a preamplifier, an A / D (Analog to Digital) converter, a quadrature detection circuit, a DMAS beamformer (described later), and the like, and performs various processes on the received signals transmitted from the ultrasonic probe 101 to generate reflected wave data (received data). The receiving circuit 112 then stores the generated reflected wave data in the buffer memory 120.

[0023] The preamplifier amplifies the received signal for each channel and performs gain adjustment (gain correction). The A / D converter converts the gain-corrected received signal into a digital signal by A / D converting the gain-corrected received signal. The quadrature detection circuit converts the digitally converted received signal into an in-phase signal (I signal, I: In-phase) and a quadrature signal (Q signal, Q: Quadrature-phase) in the baseband. The quadrature detection circuit then transmits the I signal and Q signal (IQ signal) to a DMAS beamformer. The beamformer then performs DMAS beamforming on the IQ signal and stores the data obtained by DMAS beamforming in buffer memory 120 as reflected wave data. The DMAS beamformer will be described later.

[0024] The receiving circuit 112 generates two-dimensional reflected wave data from the two-dimensional received signals transmitted from the ultrasonic probe 101. The receiving circuit 112 also generates three-dimensional reflected wave data from the three-dimensional received signals transmitted from the ultrasonic probe 101.

[0025] The buffer memory 120 is a memory that temporarily stores reflected wave data generated by the transmission / reception circuit 110. For example, the buffer memory 120 is configured to be able to store a predetermined number of frames of reflected wave data. When a new frame of reflected wave data is generated by the reception circuit 112 while the buffer memory 120 is storing the predetermined number of frames of reflected wave data, the buffer memory 120, under the control of the reception circuit 112, discards the oldest generated frame of reflected wave data and stores the newly generated frame of reflected wave data. For example, the buffer memory 120 is realized by a semiconductor memory element such as a RAM (Random Access Memory) or a flash memory.

[0026] The signal processing circuit 130 reads the reflected wave data from the buffer memory 120, performs various signal processing on the read reflected wave data, and outputs the reflected wave data that has undergone various signal processing as B-mode data or Doppler data to the image generation circuit 140. The signal processing circuit 130 is realized by, for example, a processor. The signal processing circuit 130 is an example of a signal processing unit.

[0027] For example, every time one new frame of reflected wave data is stored in the buffer memory 120, the signal processing circuit 130 reads out the new frame of reflected wave data stored in the buffer memory 120. The signal processing circuit 130 then performs various signal processing on the read one frame of reflected wave data to generate one new frame of B-mode data or Doppler data. Every time the signal processing circuit 130 generates one frame of B-mode data or Doppler data, it outputs the newly generated one frame of B-mode data or Doppler data to the image generation circuit 140. An example of the various types of signal processing performed by the signal processing circuit 130 will be described below.

[0028] For example, the signal processing circuit 130 performs quadrature detection, logarithmic amplification, envelope detection processing, etc. on the reflected wave data read out from the buffer memory 120 to generate B-mode data in which the signal strength (amplitude strength) for each sample point is expressed as luminance. For example, the signal processing circuit 130 outputs the generated B-mode data to the image generation circuit 140.

[0029] Furthermore, the signal processing circuit 130 performs frequency analysis on the reflected wave data read from the buffer memory 120 to extract motion information of the moving object (blood flow, tissue, contrast agent echo components, etc.) based on the Doppler effect from the reflected wave data, and generates Doppler data indicating the extracted motion information. For example, the signal processing circuit 130 extracts average velocity, average variance, average power value, etc. over multiple points as motion information of the moving object, and generates Doppler data indicating the extracted motion information of the moving object. The signal processing circuit 130 outputs the generated Doppler data to the image generation circuit 140.

[0030] Using the functions of the signal processing circuit 130, the ultrasound diagnostic device 1 can perform a color Doppler method, also known as a color flow mapping (CFM) method. In the color flow mapping method, ultrasonic waves are transmitted and received multiple times along multiple scan lines. The color flow mapping method applies an MTI (Moving Target Indicator) filter to a data sequence at the same position to suppress signals (clutter signals) derived from stationary or slow-moving tissues from the data sequence at the same position and extract signals (blood flow signals) derived from blood flow. The color flow mapping method then estimates blood flow information, such as blood flow velocity, blood flow dispersion, and blood flow power, from the blood flow signal. The signal processing circuit 130 outputs color image data indicating the blood flow information estimated by the color flow mapping method to the image generation circuit 140. The color image data is an example of Doppler data.

[0031] The signal processing circuit 130 is capable of processing both two-dimensional reflected wave data and three-dimensional reflected wave data.

[0032] The image generation circuitry 140 generates ultrasound image data from the B-mode data or Doppler data output from the signal processing circuitry 130. The image generation circuitry 140 is realized by a processor.

[0033] For example, the image generation circuit 140 generates two-dimensional B-mode image data that represents the intensity of the reflected wave as brightness from the two-dimensional B-mode data generated by the signal processing circuit 130. The image generation circuit 140 also generates two-dimensional Doppler image data in which motion information or blood flow information is visualized from the two-dimensional Doppler data generated by the signal processing circuit 130. The two-dimensional Doppler image data in which motion information is visualized is velocity image data, variance image data, power image data, or image data that is a combination of these.

[0034] Here, the image generation circuit 140 generally converts (scan converts) a scan line signal sequence of an ultrasound scan into a scan line signal sequence of a video format, such as that of a television, to generate ultrasound image data for display. For example, the image generation circuit 140 generates ultrasound image data for display by performing coordinate conversion on the data output from the signal processing circuit 130 in accordance with the ultrasound scanning format of the ultrasound probe 101. In addition to scan conversion, the image generation circuit 140 also performs various image processing, such as image processing (smoothing processing) that regenerates an average brightness image using multiple image frames after scan conversion, and image processing (edge ​​enhancement processing) that uses a differential filter within the image. The image generation circuit 140 also combines text information of various parameters, scales, body marks, etc. with the ultrasound image data.

[0035] Furthermore, the image generation circuit 140 generates three-dimensional B-mode image data by performing coordinate transformation on the three-dimensional B-mode data generated by the signal processing circuit 130. The image generation circuit 140 also generates three-dimensional Doppler image data by performing coordinate transformation on the three-dimensional Doppler data generated by the signal processing circuit 130. That is, the image generation circuit 140 generates "three-dimensional B-mode image data and three-dimensional Doppler image data" as "three-dimensional ultrasound image data (volume data)." The image generation circuit 140 then performs various rendering processes on the volume data to generate various types of two-dimensional image data for displaying the volume data on the display 103.

[0036] The rendering process performed by the image generation circuit 140 includes, for example, a process of generating MPR image data from volume data using multi-planar reconstruction (MPR). The rendering process performed by the image generation circuit 140 also includes, for example, a volume rendering (VR) process of generating two-dimensional image data reflecting three-dimensional information. The image generation circuit 140 is an example of an image generation unit.

[0037] The B-mode data and Doppler data are ultrasound image data before scan conversion processing, and the data generated by the image generation circuit 140 is ultrasound image data for display after scan conversion processing. Note that the B-mode data and Doppler data are also called raw data.

[0038] The image memory 150 is a memory that stores various types of image data generated by the image generation circuit 140. The image memory 150 also stores data generated by the signal processing circuit 130. The B-mode data and Doppler data stored in the image memory 150 can be called up by an operator after diagnosis, for example, and becomes ultrasound image data for display via the image generation circuit 140. For example, the image memory 150 is realized by a semiconductor memory element such as a RAM (Random Access Memory), a flash memory, or a hard disk or an optical disk.

[0039] The memory circuitry 160 stores control programs for scanning (transmitting and receiving ultrasound), image processing, and display processing, as well as various data such as diagnostic information (e.g., patient ID, doctor's findings, etc.), diagnostic protocols, and various body marks. The memory circuitry 160 is also used, as necessary, to store data stored in the image memory 150. For example, the memory circuitry 160 is realized by a semiconductor memory element such as a flash memory, a hard disk, or an optical disk.

[0040] The control circuit 170 controls the overall processing of the ultrasound diagnostic apparatus 1. Specifically, the control circuit 170 controls the processing of the transmission circuit 111, the reception circuit 112, the signal processing circuit 130, and the image generation circuit 140 based on various setting requests input by the operator via the input device 102 and various control programs and various data read from the storage circuit 160. The control circuit 170 also controls the display 103 to display an ultrasound image based on ultrasound image data for display stored in the image memory 150. For example, the control circuit 170 controls the display 103 to display a B-mode image based on B-mode image data or a color image based on color image data. The control circuit 170 also controls the display 103 to display a color image superimposed on the B-mode image. The control circuit 170 is an example of a display control unit or a control unit. The control circuit 170 is realized by, for example, a processor. An ultrasound image is an example of an image.

[0041] Furthermore, the control circuit 170 controls the ultrasonic probe 101 via the transmission / reception circuit 110, thereby controlling ultrasonic scanning.

[0042] The term "processor" used in the description refers to a circuit such as a central processing unit (CPU), a graphics processing unit (GPU), an application specific integrated circuit (ASIC), or a programmable logic device (e.g., a simple programmable logic device (SPLD), a complex programmable logic device (CPLD), or a field programmable gate array (FPGA)). The processor reads a program stored in the memory circuit 160 and executes the read program to realize its function. Instead of storing the program in the memory circuit 160, the processor may be configured so that the program is directly embedded in its circuit. In this case, the processor reads and executes the program embedded in the circuit to realize its function. Each processor in this embodiment is not limited to being configured as a single circuit, but may be configured as a single processor by combining multiple independent circuits to realize its function. 1 (for example, the signal processing circuit 130, the image generation circuit 140, and the control circuit 170) may be integrated into a single processor to realize its functions. That is, the signal processing circuit 130, the image generation circuit 140, and the control circuit 170 may be integrated into a single processing circuit realized by a processor.

[0043] The overall configuration of the ultrasound diagnostic apparatus 1 according to the embodiment has been described above. Next, an example of the configuration of a beamformer that performs DMAS beamforming in the receiving circuitry 112 will be described. FIG. 2 is a diagram showing an example of the configuration of a beamformer that performs DMAS beamforming in the receiving circuitry 112 according to the first embodiment. In the example of FIG. 2, for convenience of explanation, the number of elements in the ultrasound probe 101 is three, and one channel corresponds to one element. However, the number of elements in the ultrasound probe 101 may be N (N is a natural number) other than three. Furthermore, one channel may correspond to two or more elements. Furthermore, an element number n (n=1, 2, 3) is assigned to each element to identify the three elements. For example, the first element is assigned element number 1. The second element is assigned element number 2, and the third element is assigned element number 3.

[0044] 2, the beamformer of the receiving circuit 112 includes three delay circuits 113a to 113c, three multipliers 114a to 114c, three weighting coefficient calculation circuits 115a to 115c, three multipliers 116a to 116c, and an adder 117. The beamformer may be realized by a processor.

[0045] When the three delay circuits 113a to 113c are not distinguished from one another, they are referred to as "delay circuits 113." Similarly, when the three multipliers 114a to 114c are not distinguished from one another, they are referred to as "multipliers 114," when the three weighting coefficient calculation circuits 115a to 115c are not distinguished from one another, they are referred to as "weighting coefficient calculation circuits 115," and when the three multipliers 116a to 116c are not distinguished from one another, they are referred to as "multipliers 116."

[0046] For example, one delay circuit 113, one multiplier 114, one weighting coefficient calculation circuit 115, and one multiplier 116 are provided for one channel.

[0047] x n(t) is an IQ signal based on the received signal output from element number n, and is the IQ signal at time t. As shown in FIG. 2, the IQ signal x1(t) is input to the delay circuit 113a. The delay circuit 113a delays the IQ signal x1(t) by time τ1 and outputs it. That is, the delay circuit 113a outputs the IQ signal x1(t) delayed by time τ1 as the IQ signal s1(t) to the multiplier 114a, the multiplier 114c, the weighting coefficient calculation circuit 115a, and the weighting coefficient calculation circuit 115c. Note that x n (t) may not be an IQ signal, but may be an RF signal with only a real part.

[0048] Similarly, delay circuit 113b delays the input IQ signal x2(t) by time τ2 and outputs the IQ signal x2(t) delayed by time τ2 as IQ signal s2(t) to multiplier 114a, multiplier 114b, weighting coefficient calculation circuit 115a, and weighting coefficient calculation circuit 115b.

[0049] In addition, the delay circuit 113c delays the input IQ signal x3(t) by time τ3 and outputs the IQ signal x3(t) delayed by time τ3 as an IQ signal s3(t) to the multiplier 114b, the multiplier 114c, the weighting coefficient calculation circuit 115b, and the weighting coefficient calculation circuit 115c.

[0050] Note that time τ1 is a delay time according to the positional relationship between the position of the element with element number 1 and the position of the focal point. Time τ1 is also simply a delay time according to the position of the focal point. Similarly, time τ2 is a delay time according to the positional relationship between the position of the element with element number 2 and the position of the focal point, and time τ3 is a delay time according to the positional relationship between the position of the element with element number 3 and the position of the focal point. Time τ2 and time τ3 are also simply delay times according to the position of the focal point.

[0051] As described above, the delay circuit 113 outputs a plurality of delayed signals by applying delay times according to the position of the focal point to a plurality of reception signals output from a plurality of elements of the ultrasound probe 101. The delay circuit 113 is an example of a delay unit.

[0052] The multiplier 114a multiplies the IQ signal s1(t) by the IQ signal s2(t), and outputs the signal s1(t)s2(t) obtained as a result of the multiplication to the multiplier 116a.

[0053] Similarly, multiplier 114b multiplies IQ signal s2(t) by IQ signal s3(t) and outputs the resulting signal s2(t)s3(t) to multiplier 116b. Multiplier 114c multiplies IQ signal s3(t) by IQ signal s1(t) and outputs the resulting signal s3(t)s1(t) to multiplier 116c.

[0054] The weighting coefficient calculation circuit 115a calculates the weighting coefficients (weights) to be applied to the signals s1(t) and s2(t). A specific example of a method for calculating the weighting coefficients for the signals s1(t) and s2(t) will be described below. For example, the weighting coefficient calculation circuit 115a calculates the complex conjugate of the input signal s1(t) and calculates the weights for the signal s1(t). * (t) is derived. Note that the signal s n * (t) is the signal s n (t) is the complex conjugate of the complex number denoted by (t).

[0055] Then, the weighting coefficient calculation circuit 115a calculates the signal s1 * (t) is multiplied by the input signal s2(t), and the resulting signal s1 * (t)s2(t) phase ∠(s1 * (t)s2(t)). * (t)s2(t)) is also the phase difference (time difference) between signals s1(t) and s2(t). * (t)s2(t)) is also the correlation, correlation coefficient, phase information, and instantaneous phase value between signal s1(t) and signal s2(t).

[0056] Next, the weighting coefficient calculation circuit 115a calculates the phase ∠(s1 * For example, the weighting coefficient calculation circuit 115a calculates a weighting coefficient according to the phase ∠(s1(t)s2(t)). *The weighting coefficient calculation circuit 115a calculates a weighting coefficient w(θ(t)) that decreases as θ(θ(t)) increases. To explain this in concrete terms, the weighting coefficient calculation circuit 115a calculates the weighting coefficient w(θ(t)) using the following equation (1):

[0057]

number

[0058] In equation (1), θ(t) is the phase ∠(s1 * (t)s2(t)). That is, the weighting factor w(θ(t)) = weighting factor w(∠(s1 * (t)s2(t)). Also, in equation (1), θ is also the phase ∠(s1 * (t)s2(t)). In equation (1), α is a coefficient for adjusting the magnitude of the weighting coefficient w(θ(t)).

[0059] Then, the weighting coefficient calculation circuit 115a calculates the weighting coefficient w(∠(s1 * (t)s2(t)) is output to multiplier 116a.

[0060] Similarly, the weighting coefficient calculation circuit 115b uses the signals s2(t) and s3(t) to calculate the weighting coefficient w(∠(s2 * Then, the weighting coefficient calculation circuit 115a calculates the weighting coefficient w(∠(s2 * (t)s3(t)) is output to multiplier 116b.

[0061] Furthermore, the weighting coefficient calculation circuit 115c calculates the weighting coefficient w(∠(s3(t))) to be applied to the signal s3(t)s1(t) using the signal s3(t) and the signal s1(t) in the same way that the weighting coefficient calculation circuit 115a calculates the weighting coefficient w(θ(t)) using the signal s1(t) and the signal s2(t). *Then, the weighting coefficient calculation circuit 115a calculates the weighting coefficient w(∠(s3 * (t)s1(t)) is output to the multiplier 116c.

[0062] In this way, the weighting coefficient calculation circuit 115 calculates the weighting coefficient based on the correlation between the multiplied received signals. Also, the weighting coefficient calculation circuit 115 calculates the weighting coefficient based on the phase information between the multiplied delayed signals. The weighting coefficient calculation circuit 115 is an example of a weight calculation unit.

[0063] Then, multiplier 116a applies a weighting factor w(∠(s1 * (t)s2(t)) and the resulting signal s1 ´ (t) is output to the adder 117. Here, the weighting coefficient w(∠(s1 * As described above, the value of s1(t)s2(t) decreases as the phase difference (time difference) between the signals s1(t) and s2(t) increases. Therefore, the multiplier 116a multiplies the signal s1(t)s2(t) so that the contribution rate of the signal s1(t) to the ultrasound image data decreases as the phase difference (time difference) between the signals s1(t) and s2(t) increases. ´ (t) can be output to the adder 117. Therefore, according to the ultrasound diagnostic device 1 of this embodiment, when DMAS beamforming, which performs multiplication and addition of signals, is used as the beamforming method, it is possible to suppress the occurrence of speckle patterns.

[0064] Similarly, multiplier 116b applies a weighting factor w(∠(s2 * (t)s3(t))) and the resulting signal s2 ´ (t) to the adder 117. Furthermore, the multiplier 116c applies a weighting factor w(∠(s3 * (t)s1(t))) and the resulting signal s3 ´ (t) is output to the adder 117.

[0065] In this manner, the multiplier 116 applies the weighting factor to the signal resulting from the multiplication. The multiplier 116 is an example of an applying unit.

[0066] The adder 117 calculates the sum of all the input signals as the signal y(t). ´ (t) and signal s2 ´ (t) and signal s3 ´ The adder 117 calculates the sum of the signal y(t) and the reflected wave data as the signal y(t). The adder 117 then stores the signal y(t) in the buffer memory 120 as the reflected wave data.

[0067] As described above, the multiplier 114 multiplies the delayed signals between different elements, and the adder 117 adds the signals obtained as a result of the multiplication. The multiplier 114 and the adder 117 are an example of a multiplication and addition unit.

[0068] FIG. 3 is a flowchart showing an example of the flow of processing executed by the DMAS beamformer according to the first embodiment.

[0069] (Step S101) As shown in FIG. 3, in step S101, the delay circuit 113 delays the IQ signal, which is the received signal, and outputs the delayed signal, which is the delayed IQ signal.

[0070] (Step S102) Next, in step S102, multiplier 114 multiplies one of the two delayed signals output from different elements by the other delayed signal, and outputs the signal obtained as a result of the multiplication to multiplier .

[0071] (Step S103) Next, in step S103, the weighting coefficient calculation circuit 115 calculates the weighting coefficient w(θ(t)) and outputs the weighting coefficient w(θ(t)) to the multiplier .

[0072] (Step S104) Next, in step S104, multiplier 116 weights the signal output by multiplier 114 by multiplying the signal output by multiplier 114 by the weighting coefficient w(θ(t)) output by weighting coefficient calculation circuit 115, and outputs the weighted signal to adder 117.

[0073] (Step S105) Next, in step S105, the adder 117 calculates the sum of the signals output by all the multipliers 116 as a signal y(t), stores the calculated signal y(t) in the buffer memory 120 as reflected wave data, and ends the processing shown in FIG. 3.

[0074] Fig. 4 is a diagram showing an example of an ultrasound image based on ultrasound image data obtained using a conventional DMAS. Fig. 5 is a diagram showing an example of an ultrasound image based on ultrasound image data generated by the ultrasound diagnostic device 1 according to the first embodiment. In the ultrasound image shown in Fig. 4, a relatively strong speckle pattern appears, as indicated by the two arrows. On the other hand, in the ultrasound image shown in Fig. 5, as indicated by the two arrows, the difference in shading (intensity) of the speckle pattern is smaller compared to the ultrasound image shown in Fig. 4. Therefore, according to this embodiment, the occurrence of a speckle pattern can be suppressed.

[0075] The above has described the ultrasonic diagnostic device 1 according to the first embodiment. As described above, the ultrasonic diagnostic device 1 according to the first embodiment can suppress the occurrence of speckle patterns when DMAS beamforming, which performs signal multiplication and addition, is used as the beamforming method.

[0076] (Modification of the first embodiment) In the first embodiment described above, various types of processing may be performed on the signal output from the multiplier 114. Therefore, such a modification will be described as a modification of the first embodiment. Note that in the description of the modification of the first embodiment, differences from the first embodiment will be mainly described, and a description of the same configuration as the first embodiment may be omitted.

[0077] 6 is a diagram showing an example of the configuration of a beamformer that performs DMAS beamforming in the receiving circuit 112 according to a modification of the first embodiment. The beamformer according to the modification of the first embodiment differs from the beamformer according to the first embodiment shown in FIG. 2 in that it includes three signal processing circuits 118a to 118c.

[0078] When the three signal processing circuits 118a to 118c are not to be distinguished from one another, they are referred to as "signal processing circuits 118." For example, one signal processing circuit 118 is provided for one channel. The signal processing circuit 118 multiplies the signal s output from the multiplier 114 by i (t)s j (t) (i, j=1, 2, 3, i≠j) is input. Then, the signal processing circuit 118 processes the input signal s i (t)s j (t), the signal s is calculated by the following equation (2): i1 Calculate (t).

[0079] s i1 (t)=sign(s i (t)s j (t))·|s i (t)s j (t)| 1 / 2 (2)

[0080] In addition, in equation (2), sign(s i (t)s j As described in the above-mentioned Non-Patent Document 1 (The Delay Multiply and Sum Beamforming Algorithm in Ultrasound B-Mode Medical Imaging, IEEE Transaction 2015), for example, the signal s i (t)s j This is a function that outputs the polarity (positive or negative) of (t).

[0081] For example, the signal processing circuit 118a uses the signals s1(t) and s2(t) output from the multiplier 114a to generate a signal s 11 Then, the signal processing circuit 118a calculates the signal s 11 Similarly, the signal processing circuit 118b uses the signals s2(t) and s3(t) output from the multiplier 114b to output the signal s 21 (t), and the signal processing circuit 118c calculates the signal s3(t) and s1(t) output from the multiplier 114c. 31 Then, the signal processing circuit 118b calculates the signal s 21 (t) to the multiplier 116b, and the signal processing circuit 118c outputs the signal s 31 (t) is output to the multiplier 116c.

[0082] Then, multiplier 116a multiplies signal s 11 (t) with weighting coefficient w(∠(s1 * (t)s2(t))) and the resulting signal s 11 ´ (t) is output to the adder 117.

[0083] Similarly, multiplier 116b multiplies signal s 21 (t) with weighting coefficient w(∠(s2 * (t)s3(t))) and the resulting signal s 21 ´ (t) to the adder 117. The multiplier 116c outputs the signal s 31 (t) with weighting coefficient w(∠(s3 * (t)s1(t))) and the resulting signal s 31 ´ (t) is output to the adder 117.

[0084] The adder 117 outputs the signal s 11 ´ (t) and signal s 21 ´ (t) and signal s 31 ´The adder 117 calculates the sum of the signal y(t) and the reflected wave data as the signal y(t). The adder 117 then stores the signal y(t) in the buffer memory 120 as the reflected wave data.

[0085] The above has described the ultrasound diagnostic device 1 according to the modified example of the first embodiment. The ultrasound diagnostic device 1 according to the modified example of the first embodiment can achieve the same effects as the ultrasound diagnostic device 1 according to the first embodiment.

[0086] (Second embodiment) In the first embodiment, a case has been described in which an IQ signal obtained by a quadrature detection circuit is input to the multiplier 114. However, in the ultrasound diagnostic apparatus 1, a sub-aperture signal may be input to the multiplier 114. Therefore, such an embodiment will be described as a second embodiment. Note that in the description of the second embodiment, differences from the first embodiment will be mainly described, and a description of the same configuration as the first embodiment may be omitted.

[0087] In the second embodiment, the ultrasound probe 101 includes, for example, 3k elements (k is a natural number equal to or greater than 2). The 3k elements are divided into three sub-apertures. That is, the number of elements constituting one sub-aperture is k. In this way, the 3k elements include a plurality (three) of element groups. Each of these element groups is composed of k elements. Furthermore, a sub-aperture number m (m=1, 2, 3) is assigned to each sub-aperture to identify the three sub-apertures. For example, the first sub-aperture is assigned sub-aperture number 1. The second sub-aperture is assigned sub-aperture number 2, and the third sub-aperture is assigned sub-aperture number 3. Furthermore, in the second embodiment, the sub-aperture signal a m (t) is a signal obtained by adding together k received signals (IQ signals) at time t output from k elements that make up the sub-aperture with sub-aperture number m.

[0088] A case where the sub-aperture signal a1(t) is input to the multiplier 114a will be described below with reference to Fig. 7. Note that the sub-aperture signals a2(t) and a3(t) are also generated using the same configuration and method as those described below.

[0089] Fig. 7 is a diagram showing an example of a portion of the configuration of a beamformer according to the second embodiment. Fig. 7 shows the configuration of the stages preceding the multiplier 114a. As shown in Fig. 7, in the second embodiment, k delay circuits 113_1 to 113_k and one adder 125a are provided preceding the multiplier 114a. That is, k delay circuits 113_1 to 113_k are provided corresponding to the k elements constituting the subaperture with subaperture number 1. In this way, the subaperture beamforming section corresponding to the subaperture with subaperture number 1 includes k delay circuits 113_1 to 113_k and one adder 125a. The subaperture beamforming section outputs a subaperture signal a1(t) by delaying and adding received signals output from an element group composed of k elements.

[0090] As shown in Figure 7, the IQ signal x g (t) is input to a delay circuit 113_g, where g is a natural number between 1 and k. The delay circuit 113_g delays the IQ signal x g (t) is time τ g That is, the delay circuit 113_g outputs the signal after delaying it by a time τ g IQ signal x delayed by g (t) is the IQ signal s g (t) is output to the adder 125a.

[0091] The adder 125a calculates the sum of all the input signals as the sub-aperture signal a1(t). That is, the adder 125a calculates the sum of k IQ signals x g The adder 125a calculates the sub-aperture signal a1(t) by summing the sub-aperture signals a1(t) and a1(t) together. The adder 125a then outputs the sub-aperture signal a1(t) to the multiplier 114a (see FIG. 7), the multiplier 114c (see FIG. 2), the weighting coefficient calculation circuit 115a (see FIG. 2), and the weighting coefficient calculation circuit 115c (see FIG. 2).

[0092] In the second embodiment, the sub-aperture signal a2(t) input to the multiplier 114a, the multiplier 114b, the weighting coefficient calculation circuit 115a, and the weighting coefficient calculation circuit 115b is also generated using a configuration and method similar to those described above. The sub-aperture signal a3(t) input to the multiplier 114b, the multiplier 114c, the weighting coefficient calculation circuit 115b, and the weighting coefficient calculation circuit 115c is also generated using a configuration and method similar to those described above.

[0093] In the second embodiment, the sub-aperture signal a1(t) is used instead of the signal s1(t), the sub-aperture signal a2(t) is used instead of the signal s2(t), and the sub-aperture signal a3(t) is used instead of the signal s3(t), and the same processing as in the first embodiment is performed. Therefore, in the second embodiment, the multiplier 114 multiplies the sub-aperture signal in all combinations between the above-mentioned element groups.

[0094] Fig. 8 is a diagram showing an example of an ultrasound image based on ultrasound image data generated by the ultrasound diagnostic apparatus 1 according to the second embodiment. In the ultrasound image shown in Fig. 8, the difference in shading (intensity) of the speckle pattern is smaller than in the ultrasound image shown in Fig. 4. Therefore, according to this embodiment, the occurrence of speckle patterns can be suppressed.

[0095] The ultrasound diagnostic device 1 according to the second embodiment has been described above. The ultrasound diagnostic device 1 according to the second embodiment provides the same effects as the first embodiment. Furthermore, in the second embodiment, received signals from multiple elements are processed collectively, which shortens the calculation time for beamforming.

[0096] (Third embodiment) In the second embodiment, the delay circuits 113_1 to 113_k receive the IQ signals x1(t) to x kIn the above description, a case where each of the delay circuits 113_1 to 113_k is input is described. However, a signal of a harmonic component extracted by a pulse subtraction method (pulse inversion method) may be input to each of the delay circuits 113_1 to 113_k. That is, the ultrasonic diagnostic apparatus 1 may perform harmonic imaging by a pulse subtraction method. Therefore, such an embodiment will be described as a third embodiment. Note that in the description of the third embodiment, differences from the second embodiment will be mainly described, and a description of the same configuration as the second embodiment may be omitted.

[0097] In the third embodiment, the control circuit 170 causes each element of the ultrasonic probe 101 to perform ultrasonic scanning, which is a set of transmitting a first ultrasonic wave and transmitting a second ultrasonic wave obtained by inverting the phase of the first ultrasonic wave. Therefore, in the third embodiment, each element of the ultrasonic probe 101 transmits the first ultrasonic wave and also transmits the second ultrasonic wave obtained by inverting the phase of the first ultrasonic wave. Furthermore, each element outputs a first reception signal by receiving a reflected wave of the first ultrasonic wave, and outputs a second reception signal by receiving a reflected wave of the second ultrasonic wave.

[0098] Below, IQ signal x g (t) is the IQ signal based on the first transmitted ultrasound, and the IQ signal x g,PS A case where (t) is an IQ signal based on the second transmitted ultrasound will be described with reference to Fig. 9. Fig. 9 is a diagram showing an example of a part of the configuration of a beamformer according to the third embodiment. In the third embodiment, the sub-aperture signal a m´ (t) is the harmonic signal b at time t corresponding to the k elements constituting the sub-aperture of sub-aperture number m. g (t) is added to the sub-aperture signal a. 1´ The following describes the configuration and method for generating the sub-aperture signal a(t). 2´ (t) and sub-aperture signal a 3´ (t) is also generated.

[0099] Fig. 9 shows the configuration of the stage preceding delay circuit 113_g. As shown in Fig. 9, in the third embodiment, adder 119_g is provided preceding delay circuit 113_g. That is, k adders 119_1 to 119_k are provided corresponding to the k elements constituting the sub-aperture with sub-aperture number 1, respectively.

[0100] As shown in Figure 9, the IQ signal x g (t) and IQ signal x g,PS (t) is input to the adder 119_g. The adder 119_g outputs the IQ signal x g (t) IQ signal x g,PS (t) to obtain the harmonic signal b g (t) generates an IQ signal x g (t) is an example of the first received signal. Also, the IQ signal x g,PS (t) is an example of the second received signal. The adder 119_g then outputs the harmonic signal b g The adder 119_g outputs (t) to the delay circuit 113_g. The adder 119_g is an example of a harmonic extraction unit.

[0101] The delay circuit 113_g delays the harmonic signal b g (t) is time τ g That is, the delay circuit 113_g outputs the signal after delaying it by a time τ g The harmonic signal b delayed by g (t) is the harmonic signal s g´ (t) is output to the adder 125a.

[0102] The adder 125a calculates the sum of all the input signals as a sub-aperture signal a 1´ That is, the adder 125a calculates the k harmonic signals s g´ The sum of (t) is the sub-aperture signal a 1´ (t) and the adder 125a calculates the sub-aperture signal a 1´ (t) is output to multiplier 114a (see FIG. 9), multiplier 114c (see FIG. 2), weighting coefficient calculation circuit 115a (see FIG. 2) and weighting coefficient calculation circuit 115c (see FIG. 2).

[0103] In the third embodiment, the sub-aperture signals a input to the multipliers 114a, 114b, weighting coefficient calculation circuits 115a, and 115b are calculated by the same configuration and method as those described above. 2´ Also, by using the same configuration and method as those described above, the sub-aperture signal a(t) is input to the multiplier 114b, the multiplier 114c, the weighting coefficient calculation circuit 115b, and the weighting coefficient calculation circuit 115c. 3´ (t) is also generated.

[0104] In the third embodiment, the sub-aperture signal a1(t) is replaced with the sub-aperture signal a 1´ (t) is used, and the sub-aperture signal a2(t) is replaced by the sub-aperture signal a 2´ (t) is used, and the sub-aperture signal a 3´ (t) is used, and the same processing as in the second embodiment is performed.

[0105] The ultrasonic diagnostic device 1 according to the third embodiment has been described above. The ultrasonic diagnostic device 1 according to the third embodiment has the same effects as those of the first and second embodiments. In the third embodiment, the ultrasonic diagnostic device 1 generates an IQ signal x g (t) and IQ signal x g,PS (t) was used to explain the case where the harmonic signals are extracted by the pulse subtraction method and then delayed. However, in the third embodiment, the ultrasonic diagnostic device 1 does not extract the IQ signal x g (t) and IQ signal x g,PS After delaying (t), the delayed IQ signal x g (t) and IQ signal x g,PS (t) may be used to extract harmonic signals by pulse subtraction.

[0106] (Fourth embodiment) In the first embodiment, a case has been described in which IQ signals x1(t) to x3(t) are input to the delay circuits 113a to 113c, respectively. However, signals of harmonic components extracted by a pulse subtraction method may be input to the delay circuits 113a to 113c, respectively. That is, the ultrasound diagnostic apparatus 1 may perform harmonic imaging by a pulse subtraction method. Therefore, such an embodiment will be described as the fourth embodiment. Note that the description of the fourth embodiment will mainly focus on differences from the first to third embodiments described above, and description of configurations similar to those of the first to third embodiments may be omitted.

[0107] In the fourth embodiment, the ultrasound diagnostic device 1 performs an ultrasound beamforming method in which harmonic signals are multiplied between different elements and the signals obtained as a result of the multiplication are added. In the fourth embodiment, similar to the third embodiment, the control circuit 170 causes each element of the ultrasound probe 101 to perform ultrasound scanning, which is a set of transmitting a first ultrasound wave and transmitting a second ultrasound wave obtained by inverting the phase of the first ultrasound wave. Therefore, in the fourth embodiment, similar to the third embodiment, each element of the ultrasound probe 101 transmits a first ultrasound wave and also transmits a second ultrasound wave obtained by inverting the phase of the first ultrasound wave. Furthermore, each element outputs a first reception signal by receiving a reflected wave of the first ultrasound wave, and outputs a second reception signal by receiving a reflected wave of the second ultrasound wave.

[0108] 10 is a diagram showing an example of a portion of the configuration of a beamformer according to the fourth embodiment. Below, the configuration and method for generating harmonic signal c1(t) input to delay circuit 113a will be described, but harmonic signals c2(t) and c3(t) are also generated using a similar configuration and method. Harmonic signal c2(t) is a signal input to delay circuit 113b, and harmonic signal c3(t) is a signal input to delay circuit 113c.

[0109] Fig. 10 shows the configuration of the stage preceding the delay circuit 113a. As shown in Fig. 10, in the fourth embodiment, an adder 119_1 is provided preceding the delay circuit 113a. That is, one adder 119 is provided corresponding to one channel.

[0110] As shown in FIG. 10, the IQ signal x1(t) and the IQ signal x 1,PS (t) is input to the adder 119_1. The adder 119_1 adds the IQ signal x1(t) to the IQ signal x 1,PS The adder 119_1 generates a harmonic signal c1(t) by adding the harmonic signal c1(t) to the delay circuit 113a. The adder 119_1 then outputs the harmonic signal c1(t) to the delay circuit 113a.

[0111] The delay circuit 113a delays the harmonic signal c1(t) by a time τ1 and outputs it. That is, the delay circuit 113a outputs the harmonic signal c1(t) delayed by the time τ1 as the harmonic signal d1(t) to the multiplier 114a (see FIG. 10), the multiplier 114c (see FIG. 2), the weighting coefficient calculation circuit 115a (see FIG. 2), and the weighting coefficient calculation circuit 115c (see FIG. 2).

[0112] In the fourth embodiment, a harmonic signal c2(t) is generated and input to multiplier 114a, multiplier 114b, weighting coefficient calculation circuit 115a, and weighting coefficient calculation circuit 115b using a configuration and method similar to those described above. A harmonic signal c3(t) is generated and input to multiplier 114b, multiplier 114c, weighting coefficient calculation circuit 115b, and weighting coefficient calculation circuit 115c using a configuration and method similar to those described above. However, multiplier 114a, multiplier 114b, weighting coefficient calculation circuit 115a, and weighting coefficient calculation circuit 115b receive harmonic signal c2(t) delayed by delay circuit 113b as harmonic signal d2(t). Furthermore, the harmonic signal c3(t) delayed by the delay circuit 113c is input as the harmonic signal d3(t) to the multiplier 114b, the multiplier 114c, the weighting coefficient calculation circuit 115b, and the weighting coefficient calculation circuit 115c.

[0113] In the fourth embodiment, harmonic signal d1(t) is used instead of IQ signal s1(t), harmonic signal d2(t) is used instead of IQ signal s2(t), and harmonic signal d3(t) is used instead of IQ signal s3(t), and processing similar to that in the first embodiment is performed.

[0114] The ultrasonic diagnostic device 1 according to the fourth embodiment has been described above. The ultrasonic diagnostic device 1 according to the fourth embodiment provides the same effects as those of the first to third embodiments. In the fourth embodiment, similar to the third embodiment, the ultrasonic diagnostic device 1 generates an IQ signal x g (t) and IQ signal x g,PS In the fourth embodiment, the ultrasonic diagnostic apparatus 1 extracts the harmonic signals by the pulse subtraction method using (t) and then delays the harmonic signals. However, in the fourth embodiment, the ultrasonic diagnostic apparatus 1 does not extract the IQ signal x g (t) and IQ signal x g,PS After delaying (t), the delayed IQ signal x g (t) and IQ signal x g,PS (t) may be used to extract harmonic signals by pulse subtraction.

[0115] The program executed by the processor is provided in advance in a read-only memory (ROM) or a storage circuit. The program may be provided in a format installable or executable by these devices, recorded on a non-transitory computer-readable storage medium such as a compact disk (CD)-ROM, a flexible disk (FD), a recordable CD-R, or a digital versatile disk (DVD). The program may also be stored on a computer connected to a network such as the Internet and provided or distributed by downloading it via the network. For example, the program may be composed of modules including the above-described processing functions. In actual hardware, a CPU reads and executes the program from a storage medium such as a ROM, whereby each module is loaded into a main memory device and generated on the main memory device.

[0116] According to at least one of the embodiments described above, when DMAS beamforming, which performs multiplication and addition of signals, is used as the beamforming method, it is possible to suppress the occurrence of speckle patterns.

[0117] Although several embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0118] 1. Ultrasound diagnostic equipment 115a to 115c weighting coefficient calculation circuit 116a~116c Multiplier

Claims

1. An ultrasound diagnostic device that performs an ultrasound beamforming method in which, among a plurality of reception signals output from a plurality of elements, reception signals are multiplied between different elements and the signals obtained as a result of the multiplication are added, a weight calculation unit that calculates a weight coefficient based on the correlation between the multiplied received signals; an application unit for applying the weighting coefficient to the signal resulting from the multiplication; An ultrasound diagnostic device comprising:

2. a delay unit that applies a delay time according to a position of a focal point to the plurality of reception signals output from the plurality of elements and outputs a plurality of delayed signals; a multiplication and addition unit that multiplies the delayed signals between different elements and adds the signals obtained as a result of the multiplication; Equipped with the weight calculation unit calculates the weight coefficient based on phase information between the multiplied delayed signals. The ultrasonic diagnostic apparatus according to claim 1 .

3. the plurality of elements includes a plurality of element groups, a sub-aperture beamforming unit configured to output a sub-aperture signal by delaying and adding the received signals output from each of the element groups; the multiplication and addition unit multiplies the sub-aperture signals for all combinations between the element groups, and adds the signals obtained as a result of the multiplication; the weight calculation unit calculates the weight coefficients based on phase information between the multiplied sub-aperture signals. The ultrasonic diagnostic apparatus according to claim 2 .

4. the weight calculation unit calculates the weight coefficient based on an instantaneous phase value between the multiplied delay signals as the phase information between the multiplied delay signals. The ultrasonic diagnostic apparatus according to claim 3 .

5. the weight calculation unit calculates the weight coefficient based on a correlation coefficient between the multiplied delay signals as the phase information between the multiplied delay signals. The ultrasonic diagnostic apparatus according to claim 3 .

6. Each of the plurality of elements transmits a first ultrasonic wave and transmits a second ultrasonic wave that is an inverted phase of the first ultrasonic wave, outputs a first reception signal by receiving a reflected wave of the first ultrasonic wave, and outputs a second reception signal by receiving a reflected wave of the second ultrasonic wave, a harmonic extraction unit that extracts a harmonic signal by adding the second received signal to the first received signal output from each of the plurality of elements; Executing the ultrasound beamforming method by multiplying the harmonic signals between the different elements and adding the signals obtained as a result of the multiplication. The ultrasonic diagnostic apparatus according to claim 1 .

7. the plurality of elements includes a plurality of element groups, Each of the plurality of elements transmits a first ultrasonic wave and transmits a second ultrasonic wave that is an inverted phase of the first ultrasonic wave, outputs a first reception signal by receiving a reflected wave of the first ultrasonic wave, and outputs a second reception signal by receiving a reflected wave of the second ultrasonic wave, a harmonic extraction unit that extracts a harmonic signal by adding the second received signal to the first received signal output from each of the plurality of elements; a sub-aperture beamforming unit configured to output a sub-aperture signal by delaying and adding the harmonic signals for each of the element groups; the multiplication and addition unit multiplies the sub-aperture signals for all combinations between the element groups, and adds the signals obtained as a result of the multiplication; the weight calculation unit calculates the weight coefficients based on phase information between the multiplied sub-aperture signals. The ultrasonic diagnostic apparatus according to claim 2 .

8. A computer that executes an ultrasound beamforming method that multiplies received signals between different elements among a plurality of received signals output from a plurality of elements and adds up the signals obtained as a result of the multiplication, calculating weighting factors based on the correlation between the multiplied received signals; applying the weighting factors to the signal resulting from the multiplication; A program to execute.

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